Pipe coupling



April 3, 1962 .1. B. SMITH 3,028,150

PIPE COUPLING Filed Sept. 24, 1958 2 Sheets-Sheet 1 28 y C Q? 3 29 gENTOR.

I, JOSEPH .B-SM/TH /,2 f 12 /9 E/CHEY mm: NKkFAIlP/A/GTON 2/ 76 5F, %"M

P i A T7'OIPNEYS April 3, 1962 J. B. SMITH 3,028,180

PIPE COUPLING Filed Sept. 24, 1958 2 Sheets-Sheet 2 All z. I, I, Yg

Z III/ I a I I V P VENTOR. Ha Y/ JOSEPH -5/7/7'H 1\ \K BY AQJ 2/ R/cHEYMFI%INY&FAFPINGTON +1! 0 ATTORNEYS United States Patent Oflice 3,028,186Patented Apr. 3, 1962 3,028,180 PIPE COUPLING Joseph B. Smith, 5700Detroit Ave., Cleveland, Ohio Filed Sept. 24, 1958, Ser. No. 763,029 3Claims. (Cl. 285348) This invention relates to pipe couplings and amethod of forming them of the type that can be attached to the end of apipe or to opposed ends of separate pipes in the field and withoutthreading or special preparation of the pipe ends. The coupling of thisinvention is of the general type disclosed in my Patent 2,567,243,September 11, 1951. The coupling is particularly useful in couplingindustrial pipes including those that must withstand high pressures.Typical applications are for pipes conducting crude petroleum, gasoline,gas, asphalt, steam, etc. and many such pipes are relatively large,their size lying approximately in the range of 2 to 36 inches or largerin diameter, and the pipe connections are made in the field while thepipe is being layed or repaired and which must withstand fluid pressuresas high as 2,000 to 3,000 p.s.i.

The pipe coupling of the invention can be used in either of two ways, itcan be used as a detachable and reattachable fitting, or it can be usedas a fitting that can be attached in the field and permanently welded tothe pipe while the pipe is conducting its full capacity of fluid atworking pressure. The coupling can be used either for initial connectionof pipe ends while the pipe is being layed, or it can be used to connectreplacement lengths of pipe into an existing installation. In itsdetachable form the coupling can be removed and re-attached repeatedly,as might be the case wherein the pipe conducts fluids containing anabrasive material such as sand or the like that tends to damage therubber sealing gasket forming a part of the coupling. When the couplingis eventually to be welded in place, before the weld is made it providesa seal that is more than adequate to permit full service operation fordays or weeks after attachment, thereby insuring safe weldingconditions, and permitting clean up of surrounding oil soaked earthresulting from prior leakage, etc.

Where the coupling is used as a sleeve to join opposed pipe ends, itpermits relatively wide gaps between the ends thereby eliminating therequirement of accurate cutting to length in case of a repair insert, oraccurate lengthwise alignment of the pipe ends in case of initialinstallation.

The cost of a sleeve-type form of the coupling of this invention isabout that of a pair of conventional bolted pipe flange fittings whichfittings do require relatively accurate lengthwise alignment of the pipeends, although if a bolted flange type coupling embodying the inventionis desired, as might be the case wherein a pipe end is connected to avalve or to a pump, the same facility of dispensing with preciselengthwise alignment of the pipe is obtained.

Briefly, the coupling of the invention includes a steel sleeve thateither surrounds the pipe at both ends, or connects at one end to thepipe and is flanged at the other end. The sleeve fits the pipe looselybut is clamped to and centered on the pipe by a series of radial boltsto withstand axial forces. The sleeve is formed of good quality rolledor mild steel plate, formed into a cylinder and welded, the weld beingcarefully tested by X-ray or other means to insure that it ishomogeneous. Referring to the sleeve-type coupling, for example,adjacent each end of the steel sleeve, but spaced axially inwardlythereof, is an internal annular groove. An endless steel thrust ring isfreely slidable in the groove, which ring is initially formed as a splitring with internally beveled ends that are welded together afterinsertion into the groove in the sleeve. When this weld congeals itshrinks, reducing the circumference of the ring somewhat to give a freesliding fit that reduces tending of the ring to bind in the sleeveduring final attachment to the pipe end. With this construction thesleeve can be of rolled or mild steel even though the thrust ring iscontinuous and it is not necessary to cast the sleeve around the thrustring to attain such an assembly. A series of axial thrust bolts threadedthrough the outer end portion of the sleeve is provided to force thethrust ring axially inwardly.

After the split thrust ring is fitted into the sleeve and rendered solidby welding at its ends, a thin walled flexible metal shield is welded tothe inner wall of the guard ring which shield projects axially inwardlypast the inner edge of the thrust ring. This construction provides apartially closed annular chamber bounded by the axially inner wall ofthe internal groove in the sleeve, a portion of the circumferential wallof the groove, the inner end of the thrust ring, and the thin walledmetal shield. There is a gap between the free end of the metal shieldand the axially inner wall of the groove in the sleeve. A sealing ringof rubber-like material is fitted into the groove at the axially innerend of the thrust ring. In use, the sealing ring extrudes into theaforesaid gap and engages the wall of the pipe in response to the forceexerted against the thrust ring by setting up of the axial thrust bolts,such axial force being resisted by the action of the radial clampingbolts. The rubber sealing ring not only engages the wall of the pipe,but it flows axially along the pipe in both directions. The end or lipportion of the metal shield is forced against the pipe wall by thesealing ring and the rubber-like material flow-s into the pocket formedby the shield and the thrust ring, which action is facilitated byforming the shield as a circumferentially discontinuous member in thesense that it is readily radially inwardly deflected and reduced incircumference by the rubber ring. Preferably this action is obtained byforming the shield ring 19 with one or more axial slits. The material ofthe sealing ring also flows axially inwardly into the gap providedbetween the pipe wall and the sleeve, providing an externally elfectiveseal in this area. If a permanent or welded installation is desired,once fluid flow through the pipe is established the radial clamp boltsand the axial thrust bolts are cut ofi or are burned oil with thewelding apparatus, and the ends of the bolts are weld-sealed to thesleeve. At the same time a fillet weld is made to close the gap betweenthe end of the sleeve and the pipe and because of the construction ofthe fitting and the fact that it will seal against full line pressureand flow, the welding operation can be performed with the pipe lineconducting fluid rendering the welding operation safe and there is nodamage to the rubber sealing ring. During weldings, one of the radialclamping bolts can be removed or pierced to vent any gases that may beproduced due to fluid trapped in the spaces lying axially outwardly ofthe sealing ring.

The features and advantages of the coupling of this invention can bemore completely and specifically understood in connection with thefollowing detailed description of a preferred embodiment of theinvention taken in conjunction with the appended drawings.

In the drawings:

FIG. 1 is an elevation of an assembled sleeve type coupling embodyingthe invention, in its unwelded condition;

FIG. 2 is a section taken on 22 of FIG. 1;

FIG. 3 is a radial section taken on 3-3 of FIG. 1 showing an assembledcoupling and pipe end;

FIG. 4 is a similar section taken showing insertion of the unweldedthrust ring;

FIG. 5 is a section taken on 5-5 of FIG. 4;

FIG. 6 is a section like that of FIG. 4 taken after the 2?: thrust ringand sealing ring are in place but before the ends of the thrust ring areclosed by welding;

FIG. 7 is a section taken on 7-7 of H6. 6;

FIG. 8 is a section like that of FIG. 6 taken after the ends of thethrust ring have been welded together-the gap between the thrust ringand the sleeve established as a. result of the welding operationappears;

PEG. 9 is a section taken on 9-9 of PEG. 8;

FIG. 10 is a section like that of FIG. 3 but taken before the axialthrust bolts are set up;

FIG. 11 is a section taken on 11-11 of FIG. 10;

FIG. 12 is a radial section taken through one of the axial thrust boltsafter completion of the bolt end seal and fillet welding operations; and

FIG. 13 is an elevation of the form wherein no welding to the pipe is tobe performed so that the radial clamp bolts are locked in place withlock nuts and washers.

Referring to the embodiment of the invention of H68. 1 to 12 a sleevetype coupling C for joining the opposed ends of pipes P appears. Theassembled coupling and pipevpermits establishment of a substantial gapbetween the pipe ends as seen in FIGS. 1 and 3 which provides theadvantages relative to initial installation or replacement of a sectionreferred to. The coupling comprises a steel sleeve 10 surrounding thepipe ends, a pair of sealing rings or gaskets 11, and a pair of thrustrings 12 slidable in internal grooves 13 formed adjacent each end of thesleeve 10. The grooves 13 in the sleeve are formed with axially innerend walls 14 for axially restraining the sealing ring 11. The sleeve 10*is formed from high quality steel plate or mild steel to provide astrong joint, the edges of the formed plate being welded togetherlongitudinally at 15, FIG. 1, to render the sleeve endless.

The sealing ring 11 is preferably formed of rubber or rubber-likematerial that is relatively heat resistant such as neoprene or asilicone base rubber to insure that the sealing ring will not be damagedand will retain its nerve during the welding operation. However, sincethe welding operation is usually performed with the pipe full of flowingfluid, under certain flow conditions or with certain liquid fluidsflowing along the pipe, natural or synthetic rubber such as G-RS can beused for the sealing ring. Further, other rubber-like materialsexhibiting the characteristics of rubber can be used, such asplasticized polyvinyl chloride or the like.

The ends of sleeve lb are axially drilled and tapped as at 16 to receivea circumferential series of axial thrust bolts 17 the inner ends ofwhich bear against the axially outer edge of the thrust ring 12 in orderthat the sealing ring 11 may be deformed into sealing engagement withthe parts.

In order to initially maintain the coupling and pipes in assembledrelation and to resist axial spreading forces engendered by both thesetting up of axial thrust bolts 17 and the axial spreading efiect offluid under pressure flowing through the pipe line after the initialassembly is made, a circumferential series of radial clamp bolts 18(FIGS. 1 to 3 and 10) are threaded into tapped holes in the sleeve,these bolts having hardened, cupped ends for gripping the pipe ends.

Inorder to improve and render positive the sealing action of the rubberring 11, thin walled, flexible, metal shield ring 19, which ispreferably segmented, is welded at 21 to the inner wall of thrust ring12. These flexible shield segments project past the axially inner end ofthe thrust ring 12 forming a radially deformable lip portion 22, but theshield 19 stops short of wall 14 of the internal groove 13 formed insleeve Ill in order to provide a gap to permit extrusion of the materialof the sealing ring against the pipe wall under the force exerted by thethrust ring 12 and axial thrust bolts 17. As seen in FlG. 3, when theassembly is completed, material of the sealing ring extrudes axially inboth directions. The material presses the lip portion 22. of theflexible metal shield 19 firmly against the pipe wall and some of thematerial extrudes, as at 23, into the blind or closed pocket formed bythe deformed shield 19 and the thrust ring 12. This arrangement ofshield and thrust ring with the resulting blind pocket limits orconfines extrusion of the material of the rubber sealing ring in theaxially outward direction, thereby insuring that there will besufficient axial inward extrusion as at 24 for firm, pressure engagementbetween the thrust ring and the wall of the pipe. The seal here isimportant, because leakage past this lip either along the pipe or alongthe sleeve conducts fluid out of the coupling. The controlled extrusionof the sealing ring attained by this invention has another importantadvantage in that should'the sleeve and pipe end he clamped togethersomewhat eccentrically, because of the limited and controlled axiallyoutward extrusion of the sealing ring, there will be'amplepressure-extruded sealing ring material at the, wider spaces between thepipe and the external sleeve to provide an effective, high pressuresealentirely around the pipe.

FIGURES4 to 11 illustrate successive steps in assembling the couplingwith a pipe before the sealing ring is pressed against the pipe as shownin FIG. 3. Referring to FIGS. 4 and 5,,the initially split thrust ring12 is shown partially inserted into the sleeve, with the free ends ofthe ring overlapped to contract the'ring for insertion. The freediameter ofthe ring is at least equal to the diameter of circumferentialwall of the groove 13 in the sleeve, or the free diameter of the ringmay be somewhat greater than the groove diameter so that after insertionthe ring presses against the. outer groove wall.

It will be noted in FIGS. 5 and 7, for example, that the free ends ofthe thrust ring are beveled as at 26, to provide a pocket for receptionof the weld metal. It will also be noted in'FIG. 7 that there is a smallgap x between the radially outermost ends of the thrust ring when thelatter has assumed its expanded position in place in the sleeve groove.It has been mentioned that it is desired to provide a clearance betweenthe thrust ring and the wallof the sleeve groove when the thrust ring isin its final, endless condition to avoid binding of the ring in thegroove. This clearance, indicated at y in FIGS. 8 to 12 is automaticallyestablished after weld metal 27 has been deposited at the beveled ends26, of the thrust ring, because as the weld metal cools it shrinks andreduces the diameter of the ring.

As seen in FIG. 10, the sealing ring 11 is next inserted in the groovein sleeve 10 after which the sleeve 19 is welded as at 21' to amid-portion of the inner wall of thrust ring 12. Shield weld '21 may beeither a line weld or a tack weld because this is a mechanical jointthat need not seal against leakage of fluid. The axial thrust screws 17and the radial clamp screws 18 may now be threaded into the sleeveeither before or after insertion of the pipe P into the couplingassembly. FIG. 10 shows the pipe radially clamped and centered by clampscrews 18 before thrust screws 17 are set up to make the seal indicatedin FIG. 3.

After the various couplings in the line are assembled as shown in FIG. 3the pipe line may be opened for fluid flow under pressure, and asmentioned previously, such an assembly will in and of itself withstandhigh pressure service conditions without leakage.

FIG. 12 shows the welded condition of the assembly at one of the thrustbolts 17. The protruding ends of the bolts are cut or burned off andsealing welds 28 are made over the ends of the severed bolts, andsimilar sealing welds are made over the cut ends of clamping bolts 18.In addition, a fillet weld 29 is deposited at the gap between the end ofthe sleeve and the pipe. If any of the bolts are of high carbon steel,they may be made in the form of recessed set screws or recessed capscrews and the external recesses at the screws plug welded as disclosedand claimed in my aforesaid Patent No. 2,567,- 243.

FIG. 13 shows a coupling and pipe assembly wherein the coupling C isarranged to remain detachable and reattachable. in this form of theinvention the radial clamp bolts 18 are provided with lock nuts 36 andlock washers 37 to maintain the clamping force under vibration and otherconditions. Of course, welding operations can be performed on such anassembly by severing the bolts and proceeding as described relative tothe form of FIG. 12.

By way of example, there appears below the physical characteristics of atypical sleeve-type assembly for a large pipe, but the example is not tobe construed as limiting.

Pipe size-34 diameter% wall thickness Sleeve-16" long-2" thick steelThrust ring-2." long /s thick steel Clamp bolts28 boltssize (hardenedcup ends) Thrust screws28 hardened) Guard sleeve-2 long thick steelSealing ring-l Ag" long /s thick screws-size /s1l (may be In addition tothe advantages of the coupling of this invention explained as thisdescription of a preferred embodiment has proceeded, other advantageswill be mentioned. Although the sleeve and thrust ring are both made ofsteel and although the thrust ring lies in a groove in the sleeve, thecomplete thrust ring is endless and so presents an essentially fiatsurface to the rubber-like sealing ring regardless of variations inforce applied by the axial thrust screws during and after assembly. Thisprevents possible damage to the sealing ring adjacent the initially freeends of the thrust ring. Although the sleeve 10 may be formed of highquality steel instead of cast metal the method of assembly disclosedmakes possible the provision of an integral steel ring in an axiallyblind groove with a radial clearance between the sleeve and the groovewall. Also, there need be no welding of the sleeve after assembly withthe sealing ring or with the pipe end.

The advantages of the guard or shield 19 in the assembly in that a freeclearance between the pipe and sleeve 18 can be provided whilecontrolling the extrusion and sealing action of the rubber-like sealingring have been mentioned and greatly contribute to the effectiveness,security and safety of the assembled joint. The guard ring 19 is asimple flat (cylindrical) strip of steel, brass or the like that cannotbe accidentally dislodged and need not be interposed between the innerend face or edge of the thrust ring and the rubber-like sealing memberso that the fluid seal is between the three basic elements of theassembled coupling, namely the pipe, the sleeve and the inner exposedend of the thrust ring, so that no reliance need be placed on a fluidseal between the guard sleeve and other parts of the assembly.

It is also an advantage that there need be no bolts passing througheither the thrust ring or the sealing ring so that the thrust ring isnot weakened by bolt holes, has a smooth edge engaging the sealing ringand the thrust bolts do not conduct welding heat to the sealing ring.Also, no seal between the bolts and sealing ring need be formed.

Although the foregoing description is necessarily of a detailedcharacter, in order that the invention maybe completely set forth, it isto be understood that modifications of detail may be resorted to withoutdeparting from the scope or spirit of the invention as herein claimed.

I claim:

1. A pipe coupling comprising sleeve means for spanning a pipecircumferentially, said sleeve means having at least one axiallyoutwardly facing internal circumferential shoulder spaced axially inwardfrom one end thereof, deformable annular gasket means of elastomericmaterial inside said sleeve means and abutting said shoulder, rigidannular means inside said sleeve means with its axially inward edgeengaging the axially outward end of said gasket means, said rigidannular means having an inside diameter greater than the outsidediameter of the pipe to be coupled, flexible shield means for saidgasket means, means permanently and rigidly securing said shield meansin cantilever fashion to the radially inside face of said rigid annularmeans in continuous contact with the latter around the latters entireinternal circumference at a location thereon spaced a substantialdistance axially outward from the latters axially inward edge, saidshield means extending from said securing means axially across theradially inward face of said rigid annular means and axially at leastsubstantially half-way across the radially inward face of said gasketmeans and terminating short of the latters axially inward edge, saidshield means being so constructed and arranged as to be bendableradially along its extent axially inward from said securing means topermit extrusion of said gasket means between the radially inside faceof said rigid annular means and the radially outside face of said shieldmeans, said rigid annular means and said shield means confining saidgasket means against extrusion axially outward beyond said location ofcontinuous contact between said shield means and said rigid annularmeans and leaving the axially inward extremity of said gasket meansexposed at its radially inward face to the pressure fluid being conveyedby the pipe, said gasket means being compressed when the coupling isapplied to the pipe and urging said shield means against the pipe andextruding between said rigid annular means and said shield means.

2. The coupling of claim 1 wherein said sleeve means is a one-piecesleeve having an internal circumferential groove therein spaced axiallyinward from one end of the sleeve, and wherein said rigid annular meansis a longitudinally split thrust ring fused together at the splitholding the ring contracted to an outside diameter less than the insidediameter of said sleeve at said groove, said thrust ring being slidablyreceived in said groove.

3. The coupling of claim 1 wherein said sleeve means is a one-piecesleeve having an internal circumferential groove therein spaced axiallyinward from one end of the sleeve, said groove terminating at itsaxially inward end at said shoulder, said rigid annular means is athrust ring slidably received in said groove, and wherein axial thrustbolts extend threadedly through said one end of the sleeve and into saidgroove, said thrust bolts bearing against the axially outward end ofsaid thrust ring and being threadedly adjustable to force said thrustring axially inward against said gasket means.

References Cited in the file of this patent UNITED STATES PATENTS1,870,771 De Witt Aug. 9, 1932 2,301,296 Laurent Nov. 10, 1942 2,567,243Smith Sept. 11, 1951 2,567,527 Parks Sept. 11, 1951 2,647,769 Smith Aug.4, 1953 2,747,900 Smith May 29, 1956 2,816,472 Boughton Dec. 17, 1957

